1-Hydroxy-3-alkyl-6,6a,7,8,10,10a-hexahydro-9H-dibenzo [b,d]pyran-9-ones, their ethers and esters are disclosed in U.S. Pat. No. 3,507,885 as intermediates for the preparation of .DELTA..sup.8 or .DELTA..sup.9 -tetrahydrocannabinols (.DELTA..sup.8 or .DELTA..sup.9 -THC). No other utility than as intermediates is disclosed for these compounds.
Polyvinylpyrrolidone (PVP) has been used to increase the solubility of aromatic compounds. Among these aromatic compounds have been several useful drugs. In particular, PVP complexing has been employed to increase the solubility of the drug for intravenous injection. The following papers deal with the use of PVP in injectable preparations containing .DELTA..sup.9 -THC: D. C. Fennimore and P. R. Loy, J. Pharm. Pharmac. 23, 310 (1971) and H. Rosenkrantz et al., J. Pharm. Sci., 61, 1106 (1972). Publication detailing the use of PVP complexes with other drugs include the following: E. I. Stupak and T. R. Bates, J. Pharm. Sci., 61, 400 (1972) W. L. Chiou and S. Riegelman, ibid, 60. 1281 (1971), 58, 1505 (1969), 59, 937 (1970), G. R. Svoboda, M. J. Sweeney and W. D. Walking, ibid, 60, 33 (1971), P. Molyneux and H. Frank, J. Am. Chem. Soc., 83, 3169 (1961), T. hiquchi et al., J. Am. Pharm. Assoc., Sci. Ed., 43, 393 (1954), ibid, 398 (1954). M. Mayersohn et al., J. Pharm. Sci., 55, 1323 (1966), A. P. Simonelli et al., J. Pharm. Sci. 58, 538 (1969), and J. P. Davignon, Bull. Parent Drug Assoc., 23, 83 (1969).
U.S. Pat. No. 3,673,163 discloses and claims a coprecipitate of the tricyclic compound, acronycine, with polyvinylpyrrolidone, said co-precipitate providing an acronycine dosage form of increased solubility.
.DELTA..sup.9 -THC and other structurally related derivatives, either obtainable from natural sources or from various synthetic procedures, are known to be extremely insoluble in aqueous media. Consequently, there has been a continuing problem in determining the pharmacological activities of this group of compounds when administered by the oral route since there has been uncertainty as to the degree of absorption of these extremely insoluble substances after oral administration. Dispersions of dibenzo[b,d]pyran-9-ones with PVP or other similar materials for oral administration have not hitherto been described.